Apparatus for spraying liquids such as paints, varnishes, or the like



Sept. 3, 1935. H -r ET AL 2,013,639

APPARATUS FOR SPRAYING LIQUIDS SUCH AS PAINTS, VARNISHES OR THE LIKE Filed' Aug. 2, 1934 2 Sheets-Sheet l I? l/[ a I7] l is A 'r i a R Q a: i a a a A In V v H c. \\w I )7 v I //I 1 E I I I a Q t k5 a: (Ll k w Sept 3, 1935- H. STEINHART ET AL 2,013,539

APPARATUS FOR SPRAYING LIQUIDS sucn AS PAINTS, VARNISHES on THE LIKE Filed Aug. 2, 1934 2 Sheets-Sheet 2 Patented Sept. 3, 1935 APPARATUS FOR SPBAYING LIQUIDS SUCH AS PAINTS, VABNISHES, OR THE Hermann Steinhart, Frans In, and Ernst Baumgrats, Stuttgart, Germany, a-ignors to Robert Bosch Aktiengeaellschaft, Stuttgart,

Germany Application sum 2, 1034, Serial No. new

-In Germany All!!! 7, 1932 "lClalmaiCLMS-Q'I) The present invention relates to the spraying of liquids such as paints, varnishes or the like.

Apparatus in which compresed air is employed for spraying liquids, more especially paints, on to objects of all kinds are already known. In this method the particles of paint are carried by a current of compressed air and precipitated in the form of a spray on the obiects in question. This compressed air method however, has the drawback that a cloud of paint is formed which spreads out on all sides, and not only soils the surroundings of the working place, but also deleteriously aifects the health of the worker operating the spraying apparatus.

The further known method of placing the paint itself under pressure and blowing it out by air without mingling with the air has hitherto not been successful, because the pressures used did not produce such an atomization at the outlet of the nozzle which fulfilled all requirements in regard to a uniform application of the paint. That is a mere trickling.

The present invention is based on the recognition of the fact that the employment of pressures of at least 100 atmospheres, that is, an increase by many times of the usual pressures, is n for attaining this object. For this purpose, means are provided according to the invention for br nging the liquid to such a high pressure, for example, to several hundred atmospheres,

' that it is atonce atomized into the finest particles on emerging from a narrow nozzle, owing to the sudden relaxation of pressure and yet continues only in a single definite direction.

Two examples of construction of the invention are shown in the accompanying drawings which show hand appliances constructed in accordance with the invention.

Figure 1 is an elevation of an appliance using a piston pump, partly in section, and

Flgurelisaplan view thereof.

Figures 3-5 show details of the pump piston.

In the handle I of the appliance a small electric motor 2 is contained, the shaft 3 of which terminates in a pinion I, which gears with a toothed wheel 5. To the toothed wheel I is eccentrically fastened a pin I on which the head I of a connecting rod 3 is revolubly mounted. The connecting rod I at its other end has a ball-joint I. Theballheadofthisiointisconnectedbya nut llwiththerearend Ii ofapistonrod It. At the front end of the piston-rod I2 is a piston I! which, driven by the connecting rod, performs a reciprocating movement. It is a compression chamber situatedinfrontofthepistom' i4 is a chamber recessed out on the periphery of the piston l2. To explain the mode of working of this chamber, the piston is shown on an enlarged scale in Fig. 3. Fig. 4 shows a section through the piston on the line A-A of Fig. 3, s

and Fig. 5 is a development of the piston periphery. As will be seen from Figs. 343, the recessed part it communicates with the compression chamber it through a slot l5. l6 and It are two openings in the wall of the cylinder, which 10 are in communication with the paint supply chamber IT. The chamber I1 is connected by the pipe I. (Fig. 2) with the paint container It.

On the upward stroke of the piston, the chamher I! is filled through the openings l6, it with the paint to be sprayed. When the piston again moves forward it closes the openings l8 and It. As soon as these openings are closed the pressure on the liquid begins. The spring opposes the pressure on the valve 22 seated in the bottom of 20 thecylinder. The spring 20 is relatively weak. It has no importance for the spraying operation; it acts only as a pressure spring for the nonretum valve 22 which is adaptedto prevent the paint being again sucked back from the ante- 25 chamber of the nozzle on the backward movement of the piston. The substantial force which opposes the pressure of the paint is the force of the spring II. This spring is extremely strong. It bears at one side against the wall 23 of a spraying nozzle situated below the cylinder, and on the other side against a stop 2|, which is secured at the upper end of the nozzle needle II. As soon as the pressure of the paint overcomes the counterforce oi the spring, for instance, 100-200 atmospheres, the valve head 26 of'the nozzle needle is raised from its seat, and the paint standing under the extremely high pressure is discharged through the small opening which results into the atmosphere and at the same time atomized into 40 the finest particles.

The spraying out of the paint during each stroke lasts until in the downward movement of the piston the edge ll at the forward end of the recess It in the piston reaches the opening It 5 in the cylinder wall. The pressure of the paint immediately drops, since the pressure becomes equalized from the compression chamber I! through the slot I, the chamber it, the paint supply chamber II and the connecting pipe II to so the paint containm- II.

The quantity of paint to be sprayed by the hand appliance per stroke of the piston or per unit of time for a given piston speed may be easily adjusted by turning the piston rod I! about 66 rack-bar 28 which projects out from the pump casing (see Fig. 2) isdisplaced, the toothed ring 29, and thus also the pump piston l2, is turned about its axis. For an easy displacement of the bar 28, it may be connected to a trigger lever 28. By this means the position of the edge 2! is varied in relation to the opening l6. According as the piston is rotated in one direction or the other, a longer or a shorter time is necessary, on the downward movement of the piston, until the inclined edge 21 and thus the recessed chamber I l reaches the opening I6. The equalization of pressure, and thus the end of the spraying at each stroke consequently takes place later or earlier according to the arbitrary adjustment of the toothed rack-bar, so that the quantity of paint sprayed can be conveniently controlled in this way.

On the shaft 3 of the motor 2 is also mounted a flywheel 32 which tends to relieve the motor from the extreme variations in load as the piston l2 reciprocates in opposite directions and to ensure smooth running thereof.

In the arrangement described a relatively small motor is employed, for by the adjustment of the toothed rack-bar 28 the motor can be allowed to run idly until it has had sufficient time to accelerate all the masses.

If very large quantities of paint are to be sprayed with the apparatus described, the paint container I9 is not built on the hand appliance, but arranged at another suitable place and connected by a flexible pipe with the paint supply chamber H.

The appliance described is made in the form of a pistol, the motor being arranged in the handle and the pump in the barrel of the pistol. Other constructions could however also be employed.

The object of our invention may be also used for spraying other liquids than paint in finest particles on to objects of all kinds. The process disclosed herein is disclosed and claimed in our divisional application Serial No. 2294, filed January 17, 1935.

We declare that what we claim is:

1. An apparatus for spraying liquids such as paint, varnish or the like comprising a piston pump for compressing liquid to high pressure in which pump the piston has a recessed chamber on its periphery by which the pressure in the compression chamber and in the supply pipe is equalized and thus the effective stroke of the piston terminated when the edge of the forward end of the recessed chamber reaches the supply opening in the cylinder wall on the forward stroke of the piston, said forward edge of the recessed chamber being inclined whilst the piston is adapted for angular displacement about its own axis in order to vary the effective stroke of the piston and thus to vary the quantity of liquid delivered per stroke, a nozzle and nozzle needle tending to prevent passage of liquid through the nozzle and standing under a spring pressure and releasing only at a pressure of at least 100 atmospheres, said pumping and spraying device being arranged within the barrel of a pistol-shaped hand-appliance whilst an electric motor driving the pump is arranged within the handle of the pistol.

2. An apparatus for spraying liquids such as paint, varnish or the like comprising a piston pump for compressiing liquid to high pressure in which pump the piston has a recessed chamber on its periphery and communicating with the piston head by which the pressure in the compression chamber and in the supply pipe is equalized and thus the effective stroke of the piston terminated when the edge of the forward end of the recessed chamber reaches the supply opening in the cylinder wall on the forward stroke of the piston, said forward edge of the recessed chamher being inclined and said piston being adapted for angular displacement about its own axis in order to vary the effective stroke of the piston and thus to vary the quantity of liquid delivered per stroke, a nozzle and nozzle needle tending to prevent passage of liquid through the nozzle and standing under a spring pressure and releasing only at a pressure of at least Hi0 atmospheres, said pumping and spraying device being arranged within the barrel of a pistol-shaped hand-appliance, an electric motor for driving the pump being arranged within the handle of said appliance, a paint container arranged on said hand-appliance, and means including a trigger for effecting angular displacement of the piston.

3. A unit spray device of the character described for applying coating liquids such as paints, varnishes or the like in a spray of finely divided form comprising a nozzle, and a pump including a piston for compressing liquid to high pressure and forcing it through said nozzle, said pump piston having a recessed peripheral chamber communicating with the piston head by which the pressure in the compression chamber and supply pipe of said pump is equalized and thus the effective stroke of the piston terminated when the edge of the forward end of the recessed chamber reaches the supply opening in the pump cylinder wall on the forward stroke of said piston, said forward edge of the recessed chamber being inclined and said piston being adapted for angular displacement about its axis in order to vary the effective stroke of the piston and thus to vary the quantity of liquid delivered per stroke, and means including a trigger for effecting angular displacement of said piston.

4. A unit spray device of the character described for applying liquids such as paints, varnishes or the like in a spray of finely divided form comprising a liquid supply, a nozzle, valve means tending to prevent passage of liquid through said nozzle and loaded to release only at a pressure of at least 100 atmospheres, a pump provided with a reciprocable piston and having its discharge outlet adjacent said nozzle, and an electric motor for rapidly reciprocating said piston to intermittently apply pressure impulses' in rapid succession and at high velocity directly to relatively small quantities of said liquid to force it athigh velocity and pressure and without admixture of air through said nozzle, said pump piston having, a recessed peripheral chamber communicating with the piston head by which the pressure in the compression chamber and supply pipe of said pump is equalized and thus the effective stroke of the piston terminated when the edge of the forward end of the recessed chamber reaches the supply opening in the pump cylinder wall on the forward stroke of said piston, said forward edge of the recessed chamber being inclined and said piston being adapted for angular displacement about its axis in order to vary the effective stroke of the piston and thus to vary the quantity of liquid delivered per stroke, and means aoiaeso including a trigger for eiiectim angular displacement of said piston.

5.Aunitspraydeviceotthecharacterdescribedior applying coating liquids such as paints, varnishesorthefliheinasprayoi'flnelydivided form comprising a nozzle. a pump provided with-a reciprocabie piston and having its discharge outlet adjacent said nossle, and a motor for rapidly reciprocating said piston to intermittently apply pressure impulses in rapid succession and at high velocity directly to relatively small quantities of said liquid to force it at high velocity and pressure and without admixture of air/'through said nozzle, said piston having a recessed peripheral chamber communicating with thepiston head bywhichthepressureinthecompression chamber and supply pipe of said pump is equalized and thus the eil'ective stroke of the piston terminated when the edge oithe forward 'endoi'therecessedchamberreachesthempply opening in the pump cylinder wall on the forward stroke 02 said piston, said forward edge of .the recessedchamberbeinginclinedandsaidpiston being adapted for angular displacement about its axis in order to vary the elective stroke of the piston and thus to vary the quantity of liquid delivered per stroke, and means for eii'ecting angular displacement 0! said mstcn.

6. A portable self-contained hand spray device for applying coating liquids such as paints, varnishesorthellke-inasprayciiinelydivided iormcomprisingaliquidmpplmani-lam videdwithmeansiorlpplyingh lhresistanee tothepa-ageoiliquidtherethrm'apumpprovided with a reciprocable piston and having itsdischargeoutletadiaeent'saidnon'laanda motor for rapidlyreciprocating said pisixm to ,olairthroughsaidncsrlessasuhstantiallycmtinuous spray.

7. A portable self-contained hand spray device for applying liquids such as paints, varnishes or thelikeinasprayoi'nnelydividediormcomprising aliquid supply, anosslejalvemeanstending to prevent passage of liquid through said nozzle and loaded to release only ata pressure-oi atleast 100 atmospheres, a pump provided with a reciprocable piston and having its discharge outlet adjacent said nozzle, and a motor for rapidly reciprocating said piston t6 intermittently apply pressure impulses in rapid succession and at high velocity directly to relatively small quanflties 01' said liquid to force it at high velocity and pressureandwithmitadmixtureotairthrough said noszle as a substantially continuous spray.

' MANN S'I'EDIEART.

FRANZ KRA'IZ. ERNST BAUIGRATZ. 

